Modern optical methods such as digital shearography have attracted interest not only for laboratory investigations but also for applications on the factory floor because they can be sensitive, accurate, non-tactile and non-destructive. Optical inspection and measurement systems are more and more used in the entire manufacturing process. Shearography as a coherent optical method has been widely accepted as a useful NDT tool. It is a robust interferometric method to determine locations with maximum stress on various material structures. However, limitations of this technique can be found in the bulky equipment components, the interpretation of the complex shearographic result images and a barely solvable challenge at the work with difficult surfaces like dark absorbing or bright reflecting materials. We report a mobile shearography system that was especially designed for investigations at aircraft constructions. The great advantage of this system is the adjusted balance of all single elements to a complete measurement procedure integrated in a handy body. Only with the arrangement of all involved parameters like loading, laser source, sensor unit and software, it is feasible to get optimal measurement results.
This paper describes a complete mobile shearographic procedure including loading and image processing facilities for structural testing and flaw recognition on aircrafts. The mobile system was successfully tested, e.g. with the up-to-date EADS multi-role combat aircraft Eurofighter.
Michael Kalms, Michael Kalms,
"Mobile shearography in applications", Proc. SPIE 6762, Two- and Three-Dimensional Methods for Inspection and Metrology V, 67620K (10 October 2007); doi: 10.1117/12.735483; https://doi.org/10.1117/12.735483